160 H. MØLHOLM HANSEN 
by means of Raunkiær's circling method, the flora lists of the in- 
dividual random samples will furnish a point of departure for the 
consideration of this subject. 
This question, as well as the others referred to above, I have, 
however, been obliged to leave for future consideration, partly for 
lack of time, partly for want of suitable material. A few more 
questions, thus some investigations on the acidity of some types of 
Icelandic vegetation, and some reflections on the relation between 
plant geography and farming, will be dealt with briefly below. 
Determinations of the acidity of the soil were made simultane- 
ously with the investigation of the vegetation. The mode of proce- 
dure in taking samples of the soil and determining the degree of 
acidity was that described by Carsten Olsen (1921). For practical 
reasons the investigation was only made at Bjørk, on Lyngdalsheidi, 
and on Årnarvatnsheidi. 
For the various types of vegetation in the above-mentioned 
localities the acidity expressed in py was as follows: 
At Bjørk 
Elvnakm ok SÆLER 6.5, 6.5 average 6.5 
Arctostaphylos mo ..... 6.5, 6.5, 6.4 — 65 
Calluna-Empetrum mo . 6.4, 6.3 — 64 
TEE een; 6.0, 6.0 — 6.0 
SAUREN... aan ee 6075.17, 8.7 — 58 
Betula nana myri...... 01, 010, 5.2, 2.2 — 54 
Koemigia flag... 2:2... 6.6, 6.3 0 
On Lyngdalsheidi 
Mosathembur .......... 6.5, 6.4, 6.3, 6.3 GA 
MBA ND EE cute 22% 6 6.3, 6.3, 6.2, 6.2 — 6.3 
MO a yt sce hae Snes 6.4, 6.4, 6.4, 6.4, 6.3 — 63 
N REN IE eae BAR G2, G25 6.2.6.2 
Valen dr SS Gi, 022 GAGS 7 — 6.1 
AOA ae ne 6.0 — 6.0 
Salıx NV pret 5.3 — 5.3 
Betula nana myri. 2... 5.3, 5.1, 5.1, 5.0, 5.0, 4.8, 43 za 
GEL nee ee ee 6.1, 6.41,.6.0 — 6.1 
On Arnarvatnsheidi 
Melar nee 6:9776:8.56.7, 6:6, 6:6 — 6.7 
The level no PRE er 6.8, 6.8, 6,4, 6.3, 6.2 — 65 
